JP2014236420A - Light source module and optical transmitter receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve downsizing and consumption power reduction of an optical transmitter receiver by individually controlling transmission light and local oscillation light with one light source module.SOLUTION: The light source module includes: a single light source having light emitting surfaces facing to each other; a first optical amplifier and a second optical amplifier disposed adjacent to each of the light emitting surfaces at both sides of the light source; and a first monitor for monitoring an output of the first optical amplifier. An output power level of the first optical amplifier is controlled independently from the second optical amplifier on the basis of a monitoring result of the first monitor.

Description

  The present invention relates to a light source module and an optical transceiver using the same.

  In recent years, with the increase in transmission traffic, the demand for introducing the next generation 100 Gbit / s optical transmission system is increasing. Even next-generation optical transmission systems require the same transmission distance and frequency utilization efficiency as conventional 10 Gbit / s systems. To achieve this, optical coherent optical communication with superior optical signal-to-noise ratio (OSNR) tolerance, non-linearity tolerance, etc., compared to the NRZ (Non Return to Zero) modulation method applied in conventional systems Is being put to practical use.

  FIG. 1 is a diagram illustrating a configuration example of a general digital coherent optical transceiver 100. The optical transmitter / receiver 100 uses separate light sources for transmission and reception. The LD module 106 is used as a light source for transmission, and the LD module 104 is used as a local light source on the receiving side. A digital signal processor (DSP) 102 converts an input data signal into a signal of a predetermined modulation method, and drives a modulator 107 through a driver 105. The modulation unit 107 modulates the continuous light input from the transmission LD module 106 with the drive data signal and outputs the modulated light from the optical transceiver 100.

  On the receiving side, the input optical signal is polarization-separated by the regiver 103 and interferes with the output light of the local light emitting LD module 104 to be separated into an in-phase component and a quadrature component. The DSP 102 demodulates the received signal as an electrical signal by synchronizing the received signal with local light, removing linear distortion due to wavelength dispersion, and the like.

  A high-reflectance film is coated on the rear end face of the laser, and a low-reflectance film is coated on the output end of the front face.

  A configuration is known in which the output from the rear end face of the laser is monitored and the light output from the front end face is kept constant (see, for example, Patent Document 1). In addition, a method has been proposed that achieves miniaturization of the speedometer and low power consumption by superimposing light emitted from the front end face and the rear end face of the laser diode on the surface of the object to be measured (for example, a patent) Reference 2). In addition, a configuration has been proposed in which microprisms are arranged on the front end surface and the rear end surface of each laser element of the laser array to deflect light emitted from the front end surface and the rear end surface, thereby widening the light irradiation angle. (For example, refer to Patent Document 3).

JP 2000-124541 A JP 2005-140619 A JP 2009-135312 A

  As shown in FIG. 1, using separate light sources for transmission and reception is disadvantageous in terms of downsizing the apparatus and reducing power consumption. Therefore, as shown in FIG. 2, a configuration is conceivable in which the output of one LD module 204 is branched by a coupler 209 and the branched light is input to a modulator 207 and a receiver 203, respectively.

  However, the following problems remain in the configuration of FIG.

  The first problem is that a high output is required for the LD module 204 because loss occurs in the coupler 209. In the case of the 1: 1 coupler 209 in FIG. 2, the loss is about 4 dB.

  The second problem is that when the coupler 209 is used, it is difficult to optimize the optical transmission / reception apparatus 200 because the optical output of the transmission light and the local light cannot be adjusted individually.

  Therefore, it is an object to achieve downsizing and low power consumption of an optical transmission / reception device by individually controlling transmission light and local light emission with a single light source module.

In one aspect, the light source module is
A single light source having opposite light exit surfaces;
A first optical amplifier and a second optical amplifier disposed adjacent to each light exit surface on both sides of the light source;
A first monitor for monitoring the output of the first optical amplifier;
The output power level of the first optical amplifier is controlled independently of the second optical amplifier based on the monitoring result of the first monitor.

  The transmission light and the local light can be individually controlled by one light source module, so that the downsizing and low power consumption of the optical transceiver can be realized.

It is a schematic block diagram of a common optical transmitter / receiver. It is a figure which shows the structure which can be considered in the process leading to the structure of embodiment. It is a schematic block diagram of the laser module of 1st Embodiment. It is a schematic block diagram of the laser module of 2nd Embodiment. FIG. 5 is a plan view of a configuration in which the laser module of FIG. 4 is packaged and a cross-sectional view along an optical axis direction of an LD mounting region. It is a figure which shows the control mechanism of the laser module of FIG. It is the schematic of the optical transmission / reception apparatus using the laser module of 1st Embodiment or 2nd Embodiment. It is a schematic block diagram of the laser module of 3rd Embodiment. It is the schematic of the optical transmission / reception apparatus using the laser module of 3rd Embodiment. It is a schematic block diagram of the laser module of 4th Embodiment. It is the schematic of the optical transmission / reception apparatus using the laser module of 4th Embodiment.

<First Embodiment>
FIG. 3 is a schematic configuration diagram of the laser module 10 according to the first embodiment of the present invention. The laser module 10 includes a single semiconductor laser (LD: Laser Diode) 11. Semiconductor amplifiers (SOA: Semiconductor Optical Amplifier) 12 and 18, lenses 12 and 19, optical isolators 14 and 21, and monitors 16 and 23 are arranged on both sides along the optical axis of the LD 11, respectively. A wavelength locker 15 is disposed on one side of the LD 11.

  The LD 11 emits light from both front and rear end faces (a plane orthogonal to the optical axis). The LD 11 is generally a tunable light source such as a DFB-LD (Distributed Feedback Laser Diode) array or a DBR (Distributed Bragg Reflector), but may be a single wavelength semiconductor laser.

  The SOA 16 amplifies light output from one end face of the LD 11. The SOA 18 amplifies the light output from the other end face of the LD 11. The light amplified by the SOA 16 is output from one end side of the laser module 10 through the lens 13, the optical isolator 14, and the wavelength locker 15. The light amplified by the SOA 18 is output from the other end of the laser module 10 via the lens 19, the optical isolator 21, and the beam splitter 22.

  The laser module 10 is connected to optical transmission lines 25 and 26 via optical connectors 27 and 28. The output light of the wavelength locker 15 is coupled to an optical transmission line (for example, an optical fiber) 25 through a lens 17. The output of the beam splitter 22 is coupled to the optical transmission line 26 via the lens 24.

  The monitor 16 monitors the first output light after the SOA 12. The monitor 23 monitors the second output light after the SOA 18. The monitoring result on the monitor 16 is fed back to the SOA 12, and the monitoring result on the monitor 23 is fed back to the SOA 18.

  Light emitted from both end faces of the LD 11 is amplified by the SOA 12 and the SOA 18, and light is detected by the monitors 16 and 23 disposed at the subsequent stages of the SOAs 12 and 18. The light detected as the current is detected by a control unit (not shown), and the monitor result is fed back to the SOAs 12 and 18. Thereby, the levels of the two output lights of the laser module 10 can be individually stabilized.

  Further, the wavelength locker 15 monitors the oscillation wavelength of the LD 11. Based on the center wavelength detected by the wavelength locker 15, the oscillation wavelength of the LD 11 is controlled to lock the output wavelength to a fixed wavelength. Thereby, stabilization of the wavelength of LD11 can also be aimed at.

  In the configuration of FIG. 3, any light output from both ends of the LD 11 may be used for transmission or reception. For example, the output from the wavelength locker 15 may be used as carrier light, and the output of the beam splitter 22 may be used as local light.

  With the configuration of the first embodiment, it is possible to realize transmission light and local light used in digital coherent optical communication with one laser module 10. By using the single LD 11 as a light source and arranging the SOAs 12 and 18 at both output ends, the laser module 10 can be reduced in size and power consumption. Further, by monitoring the output light from the SOAs 12 and 18 and feeding back to the SOAs 12 and 18, the power levels of the transmission light and the local light can be individually controlled. The wavelength locker 15 can be used to stabilize the output wavelength of the LD 11.

Second Embodiment
FIG. 4 is a schematic configuration diagram of the laser module 30 of the second embodiment. In the second embodiment, the beam splitter 22 and the monitor 23 are deleted from the configuration of the first embodiment, and the outputs on both sides of the LD 31 are controlled by the monitor 36 disposed on one side.

  The laser module 30 has a single LD 31. SOAs 32 and 38, lenses 33 and 39, and optical isolators 34 and 41 are arranged on both sides of the LD 31 along the optical axis of the LD 31, respectively. A wavelength locker 35 and a monitor 36 are disposed on one side of the LD 31.

  The optical output level can be stabilized by monitoring the optical power on one side with the monitor 36 disposed at the subsequent stage of the SOA 32 and feeding back the monitoring result to each of the SOA 32 and the SOA 38. Further, the oscillation wavelength of the LD 11 can be monitored by the wavelength locker 15, and the wavelength of the LD 31 can be controlled based on the monitoring result.

  The configuration of the second embodiment can be further downsized as compared with the first embodiment. Further, similarly to the first embodiment, it is possible to stabilize the wavelengths of both transmission light and local light.

  FIG. 5 shows a more specific configuration of the laser module 30 of FIG. The laser module 30 is mounted on the package substrate 51 and packaged. On the package substrate 51, a thermoelectric cooler (TEC) 52, optical isolators 34 and 41, and a wavelength locker 35 are arranged.

  The LD 31 is mounted on the TEC 52 via the carrier 53, and the SOA 32 and the SOA 38 are arranged on both sides of the LD 31 in the optical axis direction. The output of the SOA 32 is coupled to the optical isolator 34 by a lens 33 disposed on the TEC 52. The output of the SOA 38 is coupled to the optical isolator 41 by a lens 39 disposed on the TEC 52.

  The TEC 52 is used to stabilize the temperature of the LD 31 and is connected to a drive controller (not shown). The LD 31, SOA 32, and SOA 38 can be formed monolithically on the carrier 53. When the LD 31 is composed of a DFB array, optical couplers (multiplexers) (not shown) are inserted between the LD 31 and the SOA 33 and between the LD 31 and the SOA 38.

  The output of the SOA 32 is input to the wavelength locker 35 via the lens 32 and the optical isolator 34. The wavelength locker 35 includes beam splitters 61a and 61b, an etalon 62, and photodetectors (PD) 63 and 64.

  A part of the incident light to the wavelength locker 35 is reflected by the beam splitter 61 a and guided to the PD 63 via the etalon 62. The etalon 62 has a wavelength-dependent transmittance, and transmits only light of a specific wavelength. The center wavelength of the transmitted light is detected by PD63. The detection result of the PD 63 is fed back to the TEC 52 via the drive controller (not shown) described above, and the temperature control of the LD 31 is performed. As a result, the wavelength of the LD 31 is locked to a constant wavelength.

  A part of the transmitted component of the beam splitter 61a is reflected by the beam splitter 61b and guided to the PD 64. The PD 64 is used for detecting the optical output power.

  The transmitted component of the beam splitter 61 b is coupled to the optical fiber 25 in the connector 27 via the lens 37 as one output of the laser module 30. The other output of the laser module 30 is light that passes through the SOA 38, the lens 39, and the optical isolator 41, and is coupled to the optical fiber 26 in the connector 28 via the lens 44.

  FIG. 6 shows a control mechanism 60 that feeds back the detection result of the PD 64 to the SOA 32 and the SOA 38. The PD 64 converts incident light into current. The current output from the PD 64 is detected by the current monitor 65. The output of the current monitor 65 is input to the difference circuit 67, and a difference from the reference data 66, which is another input, is detected. The detected difference is supplied to the SOA current control unit 68 for the SOA 32 and the SOA current control unit 69 for the SOA 38. The SOA current control unit 68 controls the SOA 32 in a direction that minimizes the detected difference. The SOA current control unit 69 controls the SOA 38 in a direction that minimizes the detected difference.

  In the first embodiment of FIG. 3, a specific control mechanism is not shown, but the same control mechanism as in FIG. 6 is applied. In this case, each of the currents output from the monitor 16 and the monitor 23 in FIG. 3 is monitored by the corresponding current monitor, a difference is obtained, and is individually fed back to the SOA 12 and the SOA 18.

  FIG. 7 is a schematic diagram of an optical transceiver 1A using the laser module 10 of the first embodiment or the laser module 30 of the second embodiment. In the following description, the laser module 30 is representatively shown. The optical transceiver 1A includes a DSP 2, a receiver 3, a driver 5, a modulator 7, a control unit 8, and a laser module 30.

  One output of the laser module 30 is guided to the modulator 7 as carrier light, and the other output is guided to the receiver 3 as local light. The control unit 8 is connected to the receiver 3, the driver 5, and the laser module 30. The control unit 8 includes a drive controller (not shown) that controls the TEC 52 in accordance with the control mechanism 60 of FIG. 6 and the output of the PD 63 of the wavelength locker 35.

  The DSP 2 converts the input signal into a polarization multiplexed signal, for example, and drives the modulator 7 via the driver 5. The modulator 7 modulates the carrier light (continuous light) input from the laser module 30 with the drive data signal, and outputs the modulated light from the transmission block of the optical transceiver 1A.

  The receiver 3 receives the propagated optical signal and separates the polarization. Each polarization component separated by polarization is detected by local light from the laser module 30 and separated into an in-phase component and a quadrature component, and a corresponding voltage signal is output. The DSP 2 synchronizes the received signal and local light, removes linear distortion due to wavelength dispersion, and the like, and demodulates the received signal.

  This optical transceiver 1A uses a single laser module 30 to achieve miniaturization and low power consumption.

<Third Embodiment>
FIG. 8 is a schematic configuration diagram of a laser module 70 of the third embodiment. In the third embodiment, a modulator 71 is incorporated in the laser module 70.

  The laser module 70 has a single LD 11. The SOA 12, the modulator 71, the lens 13, the optical isolator 14, and the wavelength locker 15 are arranged in this order on one side of the LD 11, and a part of the output of the wavelength locker 15 is connected to the monitor 16. The SOA 18, the lens 19, the optical isolator 21, and the beam splitter 22 are arranged in this order on the other side of the LD 11, and a part of the light separated by the beam splitter is input to the monitor 23.

  The modulator 71 is an arbitrary optical modulator such as one that uses a change in refractive index due to electric field application, one that uses a change in refractive index due to electroabsorption, or one that uses a change in refractive index due to temperature. The modulator 71 can be formed on the same substrate as the LD 11 and the SOA 12 using silicon photonics technology. A drive data signal is input from the driver 5 (see FIG. 9) to the modulator 71, and the output light of the LD 11 is modulated. In this configuration, the optical output on the side where the modulator 71 is disposed becomes the transmission light.

  The point at which one optical output level of the LD 11 is monitored by the monitor 16 at the rear stage of the SOA 12 and fed back to the SOA 12; The point that the locker 15 stabilizes the output wavelength of the LD 11 is the same as in the first embodiment.

  FIG. 9 is a schematic diagram of an optical transceiver 1B using the laser module 70 of FIG. The optical transceiver 1B includes a DSP 2, a receiver 3, a driver 5, a control unit 8, and a laser module 70.

  One output of the laser module 70 is guided to the receiver 3 as local light, and the other output is output from the optical transceiver 1B as a transmission optical signal. The control unit 8 is connected to the receiver 3, the driver 5, and the laser module 70.

  The controller 8 individually controls the SOA 12 and the SOA 18 based on the current outputs of the monitors 16 and 23 of the laser module 70. Further, the wavelength of the LD 11 is controlled according to the output of the wavelength locker 15.

  The DSP 2 converts the input signal into, for example, a polarization multiplexed signal, and drives the modulator 71 of the laser module 70 via the driver 5. The modulated signal light is output from the laser module 70.

  The receiver 3 receives the propagated optical signal and separates the polarization. Each polarization component separated by polarization is detected by local light from the laser module 70, separated into an in-phase component and a quadrature component, and a corresponding voltage signal is output. The DSP 2 synchronizes the received signal and local light, removes linear distortion due to wavelength dispersion, and the like, and demodulates the received signal.

  The optical transmission / reception device 1B of FIG. 9 can be further reduced in size by eliminating the modulator 7 arranged outside the laser module as compared with the configuration of FIG.

  The configuration in which the modulator 71 is incorporated in the laser module may be combined with the configuration in which both the SOAs 32 and 38 are controlled by one monitor output as in the second embodiment.

<Fourth embodiment>
FIG. 10 is a schematic configuration diagram of a laser module 80 of the fourth embodiment. In the first to third embodiments, two output lights are extracted in opposite directions from both ends of the laser module. In the fourth embodiment, two output lights of the laser module are extracted in directions orthogonal to each other.

  The laser module 80 has a single LD 11. SOAs 12 and 18, lenses 12 and 19, optical isolators 14 and 21, and monitors 16 and 23 are arranged on both sides along the optical axis of the LD 11, respectively. The wavelength locker 15 and the monitor 16 are disposed on one side of the LD 11, and the beam splitter 22 and the monitor 23 are disposed on the other side.

  The first output light amplified by the SOA 12 is output in a direction parallel to the optical axis of the LD 11 through the lens 13, the optical isolator 14, and the wavelength locker 15. The second output light amplified by the SOA 18 passes through the lens 19 and the optical isolator 21, and a part thereof is deflected by the beam splitter 22 in a right angle direction. The deflected light component is coupled to the optical fiber 26 in the connector 28 via the lens 24.

  The light that passes straight through the beam splitter 22 is converted into current by the monitor 23, and the current power is monitored by a control unit (not shown). The SOA 18 is controlled based on the monitoring result.

  The configuration on the side where the wavelength locker 15 is arranged is the same as in the first embodiment, and a duplicate description is omitted.

  FIG. 11 is a schematic diagram of an optical transceiver 1C using the laser module 80 of FIG. The first output light output from one end 80 a of the laser module 80 is input to the modulator 7. The second output light output from the side surface 80 b of the laser module 80 is output in a direction orthogonal to the output direction of the first output light and input to the receiver 3.

  The configurations and operations of the DSP 2, the driver 5, the modulator 7, and the control unit 8 are the same as those in the first to third embodiments, and a description thereof will be omitted.

  In general, a light source member such as a laser module is often arranged at an end of an optical transceiver. By emitting the carrier light and the local light at an angle of 90 ° with the laser module 80, the degree of freedom in mounting is improved, which is advantageous for downsizing.

  The configuration of the fourth embodiment can also be applied to the configuration in which the modulator is incorporated in the laser module in the third embodiment. In this case, the optical transceiver can be further reduced in size by arranging the laser module having the modulation function at the corner of the optical transceiver.

  The configurations of the first to fourth embodiments can be arbitrarily combined. In any configuration, it is possible to individually control transmission light and local light emission using a single laser module, and to realize downsizing and reduction in power consumption of the optical transceiver.

  Further, by arranging an additional light branching element such as a beam splitter between the lens 17 and the lens 24 or between the lens 37 and the lens 44, a light source module having two or more outputs can be realized.

The following notes are presented for the following explanation.
(Appendix 1)
A single light source having opposite light exit surfaces;
A first optical amplifier and a second optical amplifier disposed adjacent to each light exit surface on both sides of the light source;
A first monitor for monitoring the output of the first optical amplifier;
And the output power level of the first optical amplifier is controlled independently of the second optical amplifier based on the monitoring result of the first monitor.
(Appendix 2)
A second monitor for monitoring the output of the second optical amplifier;
The light source module according to claim 1, further comprising: adjusting an output power level of the second optical amplifier based on a monitoring result of the second monitor.
(Appendix 3)
The monitoring result of the first monitor is supplied to the first optical amplifier and the second optical amplifier,
The light source module according to appendix 1, wherein the output power level of the first optical amplifier and the output power level of the second optical amplifier are individually controlled based on the monitoring result.
(Appendix 4)
A wavelength locker disposed downstream of the first optical amplifier;
The light source module according to any one of appendices 1 to 3, wherein the wavelength of the light source is controlled to a constant wavelength by the wavelength locker.
(Appendix 5)
The light source module according to appendix 4, wherein the first monitor is a photodetector that detects light branched by the wavelength locker.
(Appendix 6)
Any one of the first optical amplifier and the second optical amplifier is arranged at a subsequent stage of either the first optical amplifier or the second optical amplifier and based on a drive data signal input from the outside. A modulator that modulates one of the output lights,
The light source module according to appendix 1, further comprising:
(Appendix 7)
An optical system for outputting light emitted from the light source in a direction opposite to the light source module;
The light source module according to any one of supplementary notes 1 to 6, further comprising:
(Appendix 8)
An optical system for outputting light emitted from the light source in a direction perpendicular to each other from the light source module;
The light source module according to any one of supplementary notes 1 to 6, further comprising:
(Appendix 9)
The light source module according to any one of appendices 1 to 9,
A driver that outputs a drive signal for modulating the first light output from the light source module based on a transmission signal;
A receiving unit for detecting received light with the second light output from the light source module;
A control unit that controls the output power of the first optical amplifier independently of the second optical amplifier based on the monitor output of the light source module;
An optical transmission / reception device comprising:

1A, 1B, 1C Optical transceiver 2 DSP (signal processing unit)
3 Receiver 5 Driver 7 Modulator 8 Control unit 10, 30, 70, 80 Laser module (light source module)
11 LD (light source)
12, 32 SOA (first optical amplifier)
15, 35 Wavelength locker 16, 36 Monitor (first monitor)
18, 38 SOA (second optical amplifier)
23 Monitor (second monitor)
60 Control mechanism 22 Beam splitter (optical system)

Claims (6)

A single light source having opposite light exit surfaces;
A first optical amplifier and a second optical amplifier disposed adjacent to each light exit surface on both sides of the light source;
A first monitor for monitoring the output of the first optical amplifier;
And the output power level of the first optical amplifier is controlled independently of the second optical amplifier based on the monitoring result of the first monitor. A second monitor for monitoring the output of the second optical amplifier;
The light source module according to claim 1, further comprising: adjusting an output power level of the second optical amplifier based on a monitoring result of the second monitor. The monitoring result of the first monitor is supplied to the first optical amplifier and the second optical amplifier,
The light source module according to claim 1, wherein the output power level of the first optical amplifier and the output power level of the second optical amplifier are individually controlled based on the monitoring result. A wavelength locker disposed downstream of the first optical amplifier;
The light source module according to any one of claims 1 to 3, wherein the wavelength of the light source is controlled to a constant wavelength by the wavelength locker. Any one of the first optical amplifier and the second optical amplifier is arranged at a subsequent stage of either the first optical amplifier or the second optical amplifier and based on a drive data signal input from the outside. A modulator that modulates one of the output lights,
The light source module according to claim 1, further comprising: The light source module according to any one of claims 1 to 5,
A driver that outputs a drive signal for modulating the first light output from the light source module based on a transmission signal;
A receiving unit for detecting received light with the second light output from the light source module;
A control unit that controls the output power of the first optical amplifier independently of the second optical amplifier based on the monitor output of the light source module;
An optical transmission / reception device comprising:

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